The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Diesel engines typically have higher efficiency than gasoline engines due to an increased compression ratio and a higher energy density of diesel fuel. A diesel combustion cycle produces particulates that are typically filtered from diesel exhaust gas by a particulate filter (PF) that is disposed in the exhaust stream. Over time, the PF becomes full and the trapped diesel particulate matter (PM) must be removed. To remove the PM, the PM is burned within the PF.
Burning of PM inside the PF, also known as regeneration, produces ash as a byproduct. Engine back pressure increases due to the presence of ash and trapped soot in the PF. The back pressure increase can be partially alleviated by performing regeneration. However, the remaining ash can result in a static irreversible increase in back pressure. The increase in engine back pressure subjects the engine to higher pumping losses and lowers the overall engine efficiency. Turbine efficiency falls with the increase of pumping losses, since the turbocharger struggles to push the same amount of air under these conditions. The loss in turbine efficiency translates to higher exhaust temperatures, which in turn negatively affects components of the turbocharger.